There is something like this in France, called "Congé pour création d'entreprie" (en: time off to build a company). Basically, you can leave your job (unpaid)

There is something like this in France, called "Congé pour création d'entreprie" (en: time off to build a company). Basically, you can leave your job (unpaid) but your contract still holds, so you can get back to your job if things don't go as planned.